I am asked to set some photos to 1000 pixel in order to make them smaller using the Irfan View program, but the program only accepts in megapixels. So, how many megapixels is 1000 pixel??

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    This one is certainly not a duplicate of that question. Related, maybe; duplicate, no. – osullic Nov 11 '17 at 22:27
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    I'm not sure why you say IrfanView only accepts megapixels. If you go to the Resize/Resample tool, you can specify the width or height in pixels, or as a percentage of the original. – vclaw Nov 12 '17 at 0:13
  • This is not a photography question, but a very basic grade-school arithmetic question. – Olin Lathrop Nov 15 '17 at 12:17
  • Possible duplicate of How many pixels in a megapixel? – inkista Nov 16 '17 at 5:53

Technically, 1000 pixels would be 0,001 megapixels. But that's probably not what was intended. 1000 pixels probably refers to the image width and height, whereas megapixels usually refer to area, which is the product of width and height. You might need to clarify what exactly was meant, but I guess you should resize the images so that neither width nor height exceeds 1000 pixels.

To how many megapixels this equates depends on the picture's aspect ratio.

  • If the pictures are squared, 1000 pixels times 1000 pixels is exactly 1 megapixel.
  • If they are wider than high, you should resize them to 1000 pixels in width. Then, calculate the corresponding height: (original height / original width) * 1000. The total area then is new height * 1000 = (original height / original width) * 1000 * 1000, which makes (original height / original width) megapixels.
  • If they are higher than wide, to it the other way round. You end up with (orignial width / orginal heigth) megapixels.
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One megapixel = 1,000,000 pixels; that's what mega means (plus or minus 5%, anyway); therefore 1000 pixels = 0.001 megapixels.

However, you're almost certainly doing the wrong thing here. Megapixels are generally refers to the total number of pixels in an image, whereas a measurement like "1000 pixels" generally refers to one dimension of the image. An image with a long dimension of "1000 pixels" and a 4:3 aspect ratio (typical of smartphones) would be 1000 x 750 pixels = 750,000 pixels = 0.75 megapixels. You need to find out what you're actually be asked to do, and make sure you're doing that.

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    well i was asked to make them to 1000 'pixel' in order to upload them to a website so it might be that 1000 is meant for width and height, right? – Does it matter Nov 11 '17 at 19:23
  • i just made the width and height 1000 but the file size became bigger and i don't think that this is what it's meant – Does it matter Nov 11 '17 at 19:25
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    It might be. But you should ask whoever set you this task, not me. Also note you can't just make arbitrary images 1000 x 1000 without cropping, so once again, you need to ask... – Philip Kendall Nov 11 '17 at 19:25

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